Pulse-width modulation of pulse-code modulated signals at selectable or dynamically varying sample rates
US7626519B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | May 27, 2008 |
| Grant date | Dec 1, 2009 |
| Priority date | — |
| Expiry date | May 27, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L19/10
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Digital audio circuitry including modulation circuitry (35; 135) for generating a pulse-width modulated (PWM) signal from processed pulse-code modulated (PCM) audio signals. The modulation circuitry includes a duration quantizer function (32) that generates a sequence of duration values d(k) from received PCM samples, quantized to integer multiples of periods of a master PWM clock (CLKpwm). The duration quantizer function also produces a feedback PCM value x(k) from each quantized duration value d(k) that is applied to a loop filter (36), the output of which modifies the received PCM sample stream to suppress quantization noise. Transient effects caused by modulation or abrupt changes in the desired PWM period are suppressed by digitally filtering (34; 134) the PWM period sample stream.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.